New answers tagged ms-project
In your screen shot, take note of the name of the current view you're on: "Tasks Summary" (it's in a dropdown towards the right side of the ribbon). Then: go to the gear icon in the upper right --> PWA settings --> Manage Views Scroll down, find and click on "Tasks Summary" In the "table and fields" section, add or rearrange fields as needed.
There are three places where columns can be defined: list/library, site (SPWeb) and site collection (SPSite). Check all three and you will find them, in your case you're probably looking from too high level, e.g., looking at site collection level, when columns are in fact only created to specific site (SPWeb).
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